Strong-Field and Ultrafast Processes

强场和超快过程

• 批准号: 2208078
• 负责人: Jean Marcel Ngoko Djiokap
• 金额: $ 20万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2208078&HistoricalAwards=false
• 关键词: Strong; Field; Ultrafast; Processes

This project aims to describe the interaction of intense coherent radiation with large quantum systems, and to image and control the correlated dynamical electronic processes in atoms by using ultrafast external fields. The challenge in the theoretical description of such processes resides in the difficulty in describing accurately the time-dependent interactions between particles including the strong oscillatory fields. The basic research supported by this project will provide insights into photochemical processes and contribute broadly towards efforts to control matter on an atomic scale. A postdoctoral researcher involved with this project will be given a broad education in theoretical atomic, molecular, and optical physics, in computational physics, and in ultra-cold atom physics; first-hand experience in all aspects of scientific communication, and in teaching undergraduates at a large Big 10 Land Grant university. In addition, this work will contribute to broadening participation in STEM education since the PI, an underrepresented minority, will serve as a role model for students from underrepresented groups.The time-dependent studies in strong-field physics will promote the understanding of nonlinear and correlated elementary processes, such as non-sequential double ionization (NSDI) and above-threshold ionization (ATI) of two-active-electron atomic systems. Specific investigations supported in this project include a full control of a particular channel in NSDI of He atoms by tuning parameters of the time-delayed IR and XUV fields. Control of photoelectron wave packets leading to spiral vortices from ATI demonstrates its coherence (wave) nature, which is expected to occur in several branches of science, is illustrated here in cold-atom physics. By emulating the basic pattern of spiral vortices in ultracold-atom physics, this research seeks to establish ultracold-atom quantum simulators as a complementary tool for investigating ultrafast dynamics not only for small but also for larger quantum systems. To overcome the challenge described above, this program aims to develop some theoretical time-dependent approaches (that go beyond the single-active-electron approximation). In particular, for two-electron systems the group has developed efficient, optimized, and accurate numerical methods to solve the full-dimensional time-dependent Schrödinger equation. For larger quantum systems, they propose to use ultracold-atom quantum simulators, which will be illustrated here for the case of one- and two-electron atoms as proof-of-principle calculations. The recent experimental development by David Weld from UCSB highlighted the critical need for and timeliness of this project.This project is jointly funded by the Atomic, Molecular, and Optical Physics Theory Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目旨在描述强相干辐射与大量子系统的相互作用，并利用超快外场成像和控制原子中的相关动力学电子过程。在理论上描述这样的过程的挑战在于，在精确地描述粒子之间的相互作用，包括强振荡场的时间依赖性的困难。该项目支持的基础研究将提供对光化学过程的深入了解，并为在原子尺度上控制物质的努力做出广泛贡献。参与该项目的博士后研究人员将在理论原子，分子和光学物理学，计算物理学和超冷原子物理学方面获得广泛的教育;在科学传播的各个方面的第一手经验，以及在大型Big 10 Land Grant大学教授本科生。此外，作为代表性不足的少数民族，PI将成为代表性不足的学生的榜样，这一工作将有助于扩大STEM教育的参与。强场物理中的时间依赖性研究将促进对非线性和相关基本过程的理解，如双活性电子原子系统的非顺序双电离（NSDI）和阈上电离（ATI）。该项目支持的具体研究包括通过调整延时IR和XUV场的参数来完全控制He原子NSDI中的特定通道。控制光电子波包导致螺旋涡从ATI证明其相干性（波）的性质，这是预计将发生在几个科学分支，在这里说明冷原子物理。通过模拟超冷原子物理学中螺旋涡旋的基本模式，本研究旨在建立超冷原子量子模拟器作为研究超快动力学的补充工具，不仅适用于小型量子系统，也适用于大型量子系统。为了克服上述挑战，该计划旨在开发一些理论上的时间依赖性方法（超越单活性电子近似）。特别是，对于双电子系统，该小组已经开发出高效，优化和精确的数值方法来求解全维含时薛定谔方程。对于更大的量子系统，他们建议使用超冷原子量子模拟器，这里将针对单电子和双电子原子的情况进行说明，作为原理证明计算。最近由UCSB的大卫焊接的实验发展突出了这个项目的迫切需要和及时性。这个项目是由原子，分子，和光学物理理论程序和既定的程序，以刺激竞争力的研究（EPSCoR）该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查进行评估，被认为值得支持的搜索.